Point particle E-models

We show that the same algebraic data that permit to construct the Lax pair and the $r$-matrix of an integrable non-linear $\sigma$-model in $1+1$ dimensions can be also used for the construction of Lax pairs and of $r$-matrices of several other non-trivial integrable theories in $1+0$ dimension. We call those new integrable theories the point particle ${\cal E}$-models, we describe their structure and give their physical interpretation. We work out in detail the point particle ${\cal E}$-models associated to the bi-Yang-Baxter deformation of the $SU(N)$ principal chiral model. In particular, for each complex flag manifold we thus obtain a two-parameter family of integrable models living on it.